do fish feel pain?

drferox:

Such a deceptively simple looking question has been hotly debated in science for decades now, with vocal advocates on both sides, but I’m pretty damn sure fish feel pain.

The crux of the ‘No’ argument is basically that while fish have nociceptors (neurons which detect pain) but they don’t connect to their neocortex like they do in mammals, so they conclude that while fish probably feel some kind of ‘fish pain’ it’s not equivalent to pain as we know it.

I, personally, am not terribly impressed by this argument. We used to say this about every non-human species on the planet and now we know better.

This article from the Smithsonian sums it up well. We do know quite a lot about how fish perceive their environment, including painful stimuli.

• Stimuli that would cause pain in a human cause increased activity in the whole brain, not just the brain stem, which implies it is percieved consciously.
• Fish behaviour changes when injected with something painful, but does not change if injected with both something painful and morphine. Morphine does not change the tissue damage, only how the conscious brain perceives pain.
• Fish avoid painful stimuli.

So the evidence is mounting that yes, fish feel a type of pain and while it may not be 100% analogous to pain sensation in a mammal, that difference is likely academic. The fact that their behavior normalizes when given pain relief after a painful stimulus is pretty strong evidence in my professional opinion.

What we do know, without doubt, is that fish can suffer. The details of that pain don’t matter so much as their ability to suffer because of it. We can debate semantics and fine details all day, but if we have stewardship over these animals, it’s our duty to minimize their suffering wherever we reasonably can.

This isn’t exactly a scientific study, but if you watch injured fish, they act differently. They hang still in the water instead of moving with the others, they dull their colors, they clamp their fins, they try to avoid moving the injured part of them. Those aren’t good things to do, they make the injured fish a target. 

Most non-domesticated animals, especially less social ones, are good at concealing pain. In addition, non-mammals don’t always express pain in ways that we automatically see as expressions of distress. It’s there, though.